It has been well known among automotive engineers that performance characteristics of vehicles with carburetor-equipped fuel systems have markedly inferior performance and fuel consumption characteristics than engines equipped with fuel injection systems. This is due to the fact that the fuel and air charge to each cylinder can be accurately metered and controlled with a fuel injection system whereas the fuel air ratio of the mixture delivered to the cylinders of an eight cylinder carburetor-controlled engine typically ranges between 0.057 for the leanest cylinder to 0.090 for the richest cylinder. The fuel air ratio supplied to the remaining cylinders varies widely from one another but lie between these two extremes.
Until recently fuel costs have been so low that the related inefficiencies and losses in performance were generally acceptable by the public. However, other users were not as complaisant and numerous efforts have been made by innovators and designers to achieve more complete fuel and air mixture both at the carburetor and particularly in the area between the carburetor outlet and the engine cylinders. Typical patents disclosing these prior proposals include Lohn U.S. Pat. No. Re. 27,378; McKeever U.S. Pat. No. 1,581,461; Welling U.S. Pat. No. 1,866,829; Herbst U.S. Pat. No. 2,793,152; Gaffra U.S. Pat. No. 3,077,391; Herbst U.S. Pat. No. 3,114,669; Hanff U.S. Pat. No. 4,105,574; Hoots U.S. Pat. No. 4,024,849; Hoots U.S. Pat. No. 4,031,876; Gaylord 4,086,899; Ikegaya U.S. Pat. No. 4,153,029; Longobardi U.S. Pat. No. 4,187,819; Bouteleux U.S. Pat. No. 3,414,242; Ader U.S. Pat. No. 3,827,416; Konomi U.S. Pat. No. 4,019,483; and Ibbott U.S. Pat. No. 4,088,104.
Lohn merely proposes an adaptor plate for coupling a carburetor to the intake manifold and features flaring fuel mixture passages solely to facilitate mounting either a small or a large carburetor on an engine having a large manifold and likewise permitting either type carburetor to be mounted on an engine having a small intake manifold. McKeever proposes to promote better mixing of the fuel and air en route to the manifold by inducting a curtain of air crosswise of the fuel and air mixture en route to the manifold. Welling provides a frusto-spherical passageway at the carburetor outlet having a diametric partition with forwardly converging sidwalls cooperating with one another to set up two oppositely directed eddy currents within the entrance to the inlet manifold. The partition is located between the two eddy currents and acts as a barrier to fuel flow into one set of eddy currents thereby nullifying his objective, Guffra proposes three plates secured across the carburetor outlet and two of which have spirally disposed blades in the path of the fuel mixture causing it to swirl to aid mixing and vaporization of the fuel and one of which has by-pass aperatures for recirculating some of the mixture. The two Herbst patents merely propose a laminated sealing gasket and a method of making the same for insertion between a carburetor and an intake manifold to prevent excessive heat transfer from the engine to the carburetor. Bouteleux discloses a fuel homogenizer having valve controlled passages for inducing auxiliary or secondary air into the fuel and air mixture discharging from the carburetor and said to aid engine idling, reduce fuel consumption while regularizing cylinder temperatures, and to improve combustion. Hanff provides an enlarged chamber between his carburetor and the intake manifold enclosing a spoked diaphragm to stimulate turbulence in the fuel-air mixture and promote vaporization of the fuel. Hoots proposes the insertion of a three quarter inch plate between the carburetor and the manifold having a converging fuel and air passageway supporting a multiplicity of 15 to 25 layers of 400 mesh screen to aid fuel vaporization. Fuel not vaporized is withdrawn and returned to the carburetor. Such screening seriously interferes with air flow and deposits of fuel additives would quickly render the device inoperative. Ader proposes an accessory interconnecting both the intake and the exhaust manifolds to the carburetor outlet. This accessory circulates hot exhaust gases past thin walled sleeves conveying the fuel and air mixture to the intake manifold thereby to preheat the mixture and to vaporize the fuel. Specially designed manifolds are necessary for use with this accessory. Gaylord proposes a spacer for installation between the carburetor and manifold formed of a multiplicity of laminations alternate ones of which have larger openings for the fuel and air mixture than the remaining laminations and alleged to create turbulence to promote fuel and air mixing. Ikegaya seeks to achieve similar results by providing a spacer having a helical or inclined ledge in the air passage wall along which a film of fuel flows while evaporating. Longobardi proposes a spiral spring in the path of the fuel and air mixture to produce a spiralling vortex to enhance mixing and vaporization of fuel. Konomi proposes a variety of sleeves having various deflecting baffles at their outlet end for redirecting the fuel and air mixture downstream from the carburetor and within the intake manifold. Some embodiments are designed for use in the primary air stream and others in the secondary air stream. Ibbott discloses a tapered porous sleeve downstream from the carburetor intended to create a pressure differential across its wall claimed as useful in aiding vaporization of fuel and in reducing carbon monoxide in the exhaust gases.
The foregoing and other proposals for original equipment manufacture carburetor regulated fuel feeding systems (commonly designated OEM) have overlooked and disregarded major causes of unequal ratios of fuel and air fed to the engine cylinders, namely, the introduction of liquid fuel on one side of the butterfly valve, and closely spaced to one branch only of the intake manifold under conditions not adequately conducive to rapid vaporization of the fuel and in a manner providing grossly different fuel and air ratios. These fuel and air ratios differ from 0.057 for the leanest cylinder to 0.082 for the richest cylinder.